1. Field of the Invention
This invention relates to rotary chemical treaters which apply a film-forming liquid to the surface of an object such as a semiconductor device wafer and a liquid crystal panel board, remove the liquid adhered to the surface of the object by rotating, and make developing and wet etching.
2. Description of the Related Art
For the rotary chemical treaters which are used to apply a thin film forming liquid to wafers and glass substrates, spinner type and rotary cup type rotary chemical treaters have been put to practical use.
The spinner type rotary chemical treater causes a spinner chuck to be exposed into a fixed cup to fix an object within the cup on the spinner chuck. The object is integrally rotated with the spinner chuck. This rotation generates centrifugal force to uniformly spread an application liquid, which has been dripped onto the surface of the objective part, over the surface of the objective part.
In the above chemical treater, the cup is fixed and the spinner chuck therein is rotated, resulting in producing a turbulent gas or fluid flow within the cup. As a result, it is difficult to apply the liquid uniformly, and very small dust particles adhere to the spread film, possibly deteriorating a production yield due to quality problems.
In view of above, Japanese Unexamined Patent Publication No. 3-293056 discloses a device for preventing the application atmosphere from being disturbed. What is disclosed therein is a rotary cup type chemical treater (coater). In this device, an inner cup is placed within a fixed outer cup, an object is placed in the inner cup, the top opening of the inner cup is closed with a lid, then the inner cup is rotated.
Even with the rotary chemical treater of either of the above spinner type or rotary cup type, the application liquid may reach the back face of the object or adhere to the inner wall of the cup. And, when the liquid is left as it is, it dries to become dust, which may adhere to the surface of the object in a later step.
Therefore, for the spinner type treater, a structure which injects a cleaning fluid from the peripheral edge of the spinner toward the back face of the object has been proposed. And, for the rotary cup type treater, a structure has been proposed which lifts the lid upward, exposes movable cleaning nozzles toward the inner cup interior, a cleaning fluid is dripped into the inner cup, and the inner cup is rotated.
With the rotary chemical treater of either of the above spinner type or rotary cup type, the object is generally sucked and fixed by a vacuum source to the spinner chuck. When the vacuum chuck sucks and fixes the object, an adsorption face may cause a temperature difference, or minute dust particles adhered to the adsorption face is transferred to the object, causing a disadvantage of adversely affecting the object. In particular, this disadvantage becomes noticeable when a large glass substrate is treated as the object.
Therefore, as a fixing means which does not use the vacuum chuck, a means, which holds the peripheral edge of the object by a fastening member such as pins disposed on the top of the spinner and rotates the object integrally with the spinner or the inner cup, has been proposed.
Even with the rotary chemical treater of either of the above spinner type or rotary cup type, cleaning of the treater itself and the back face of the objective part has the following problems. Namely, the rotary cup type chemical treater using the movable cleaning nozzle can clean the inner wall of the inner cup but cannot clean the underside of the lid. Therefore, the underside of the lid must be cleaned manually, the work is troublesome and complicated, labor is required, and automation is prevented.
On the other hand, employing a means for injecting the cleaning fluid from the bottom of the inner cup can clean the underside of the lid. But, a high-speed rotation of the inner cup makes it difficult to seal a joint between the inner cup and a cleaning fluid supply section to inject the cleaning fluid from the inner cup.
When the object is rotated by a, fixing means other than the vacuum chuck, the application liquid which reaches the back face of the object is required to be removed, but the cleaning mechanism provided with the vacuum chuck cannot be applied as it is.
More specifically, to fix the object by the above vacuum chuck, cleaning fluid injecting ports directed outward are disposed partly on the vacuum chuck having a smaller diameter than the object. When the fixing means for holding the outer periphery of the object by the fastening member is used, effective locations are required to be selected for the cleaning fluid injecting ports.
In this case, the effective locations for the cleaning fluid injecting ports may be where the cleaning fluid injecting ports cannot be disposed in the treater using the vacuum chuck, e.g., the center of the spinner or the inner cup. However, it is difficult to seal a joint of the rotary section and the cleaning fluid supply section as discussed above.